Vehicle door latch systems are well known in the art. Typically, a vehicle door will have a latch for engaging and cinching onto a striker. The door will have an inside handle and an outside handle for releasing the latch and opening the door. Additionally, the door will have a lock for preventing the door from being opened by either the inside handle or the outside handle or both. For selected doors, the door is provided with a key cylinder for locking and unlocking the doors.
Optionally, vehicles can be provided with a power option. Each door latch is provided with a servo-actuator for locking and unlocking the door latches. The servo-actuators are electrically connected to a common station for effecting selected and ganged operation of the locks. The common station is now usually provided with a receiver which responds to a transmitter for remotely locking and unlocking the doors.
Additionally, rear doors are commonly provided with a lever for disabling the inside door handle for child proofing the vehicle.
Notwithstanding the ability to lock or disable the doors of the vehicle, the vehicle is still susceptible to theft by the use of a tool known as a "slim-jim". The "slim-jim" tool is inserted between the window and the window seal to manipulate the connecting rods between the looking lever or the release handle and the door latch. The "slim-jim" tool will either unlock or open the door allowing the thief access to the vehicle.
In order to increase the security level of the vehicle, some manufacturers have resorted to incorporating a dead bolt or double lock into the latch assemblies. The double lock feature disables the inside locking levers and release handles of each door making the "slim-jim" tool ineffective. Additionally if the thief were to break the window to gain entry, the thief would not be able to open any other doors and would thus be required to exit through the broken window.
Examples of such dead bolt or double lock devices are described in the following patents and publications: U.S. Pat. Nos. 4,342,209; 4,921,286; 4,492,395; 5,092,638; 5,438,855 and Japanese patent application no. JP94200101.
The prior art double lock devices generally require complex linkages and assemblies. As a result, the double lock feature cannot easily be added to a vehicle during assembly. Thus, the feature has only been available only limited luxury vehicles.